Theory of elementary particle is entering a new era by new data from the Large
Hadron Collider. Non-vanishing neutrino masses represent firm observational evidence
of new physics beyond the Standard Model. One of the most successful models
which describes new physics beyond the Standard Model is the B − L (Baryon minus
Lepton number) supersymmetric (SUSY) extension of the Standard Model (SM),
based on SU(3)C × SU(2)L × U(1)Y × U(1)B−L symmetry. In this model, three SM
singlet fermions arise quite naturally due to the U(1)B−L anomaly cancellation conditions.
These particles are accounted for right-handed neutrinos, and hence a natural
explanation for the seesaw mechanism is obtained. The masses of these right-handed
neutrinos are of order the B − L breaking scale. The B − L Higgs potential receives
large radiative corrections that induce spontaneous B−L symmetry breaking at TeV
scale, in analogy to the electroweak symmetry breaking in MSSM
In this thesis we systematically analyze the low energy implications of SUSY B−L
model with inverse seesaw mechanism. we calculate the one-loop radiative corrections
due to right-handed (s)neutrinos to the mass of the lightest Higgs boson when the
latter is Standard Model like. We show that such effects can be as large as O(100)
GeV, thereby giving an absolute upper limit on such a mass around 180 GeV. The
importance of this result from a phenomenological point of view is twofold. On the
one hand, this enhancement greatly reconciles theory and experiment, by alleviating
the so-called ‘little hierarchy problem’ of the minimal SUSY realization, whereby the
current experimental limit on the SM-like Higgs mass is very near its absolute upper
limit predicted theoretically, of 130 GeV. On the other hand, a Standard Model like
Higgs boson with mass below 180 GeV is still well within the reach of the Large
Hadron Collider, so that the SUSY realization discussed here is just as testable as
the minimal version.
We also explore right-handed sneutrino-antisneutrino mixing in the context of
SUSY B − L model where a type I seesaw mechanism of light neutrino mass generation
is naturally implemented. The constraints imposed on the mass splitting
between heavy right-handed sneutrino and the corresponding antisneutrino by the
experimental limits set on the light neutrino masses are investigated. We also study
direct pair production of such right-handed sneutrinos at the Large Hadron Collider
and its decay modes, emphasizing that their decay into same-sign di-lepton pairs are
salient features for probing these particles at the CERN machine. Finally, the charge
asymmetry present in such same-sign di-lepton signals is also analyzed and confirms
itself as a further useful handle to extract information about the oscillation dynamics.
